Crane



June 17, 1924.

A. E. JOHNSON CRANE Filed June 28, 1922 2 Sheets-Sheet 1 June 17, 1924.

` A. E. JOHNSON CRANE Filed June 28 1922 Z5 FIG. 4

" mvEN-TOR Patented June 17, 1924.

UNITED STATES ALLAN E. JOHNSON, OF KENTON, OHIO.

CRANE.

i .application fiiea June 2s, i922. serial No. 571,367.

To all whom t may concern:

Be it known that l, ALLAN E. JOHNSON, a citizen of the United States, and resident of Kenton, in the county of Hardin and State of Chio, have invented a new and useful Improvement in Cranes; and l do here- 1y declare the :following to be a full, clear, and exact description thereof.

My invention relates to cranes, and it has special reference to the vtype of crane in which a frame, platform or bed is supported upon a car or truck having wheels or their equivalent adapted to run on tracks or rails, or upon the ground or other surface, and in which the bed is supported for rotation about a verticalaxis and carries a boom or strut so connected to the bed as to be rotatable about a horizontal axis. This type of crane is commonly provided, at or near the upper end of the boom, with means for attaching tackle for lifting loads, and also with means for varying the inclination of the boom" for the purpose of varying the radial distance of the lifting tackle from the vertical axis of rotation of the bed, which radial distance is termed the working radius.

rlhe general object of my invention is to provide a crane of the above-indicated character which shall have, at various working radii, a greater lifting capacity in proportion to the weight of the crane than is possible in cranes of this class as ordinarily constructed.

More specifically, the object of my invention is to increase the lifting capacity of cranes of the indicated type by counterweighting the boom and its related parts by means of auxiliary movable counterweights so connected as to automatically move in response to changes in the inclination of the boom, whereby, when the boom is lowered or raised and therefore increases or decreases the working radius between the vertical axis and the point of support of the lifting tackle, the counterweights are moved in a direction approximately parallel to the longitudinal center line of the bed and to suoli an extent that the center of gravity of the bed, the boom, and all other parts carried by the bed, exclusive of loads, .is thus kept substantially fixed or within predetermined limits, for all working positions of the boom.

In the accompanying drawing, Fig. 1 is a side elevational view, with parts in section, of a railway crane constructed in accordance with my invention; Fig. 2 is a plan view of the construction shown in Fig. 1; Fig. 3 is an enlarged side elevational v'view of the counterweights and the mechanism by which these weights are supported and shifted; Fig. 4 is a plan view, with parts in section, of the construction of Fig. 3; Fig. 5 is a vertical sectional view of the parts shown liii Figs. 3 and 4, the section being taken substantially on the line V-V, Fig. 4; Fig. 6 is a. fragmentary side elevational view showing modified means for connecting the lower end of the boom to the sliding racks; Fig. 7 'is an elevational view of a modiiied form of gearing between the boom and the weight, and Fig. 8 is a vertical sectional view of the construction shown in Fig. 7.

y In the drawing, the numerall indicates a truck carrying a rotatable bedQ upon which a boom 3 is pivoted by means of pivot pins 4. The truck 1 is mounted upon suitable wheels 5 ruiming upon tracks 6. It will be understood, however, that my invention is not restricted to railway cranes, but, as stated above, may be provided with other ysupporting and transporting means.

The bed 2 is rotatably mounted upon a pin 7 which is usually fixed in the truck and has a head or collar 8 to prevent the bed from lifting with respect to the truck. The bed 2 carries conical rollers 9 which run upon a iixed track 10 carried by the truck 1.

The boom 3 carries, at or near its outer end, a pin 11 supporting a sheave 12 around which passes a hoisting rope 13 from which the load may be suspended in any suitable manner.

3 at some distance from the pivot pins 4 and is used to swing the boom vertically around the pins 4. The ropes 13 and 14 are wound upon drums 15 and 16, respectively, which are supported upon a bracket 17 carried by the bed 2.

The parts thus far described are such as are found in ordinary locomotive cranes, and are here shown for the purpose of illustrating one form of crane to which my invention may be applied. The only essential parts, however, so far as the application of my invention is concerned, are the bed supported upon a truck in any manner which will permit rotatable movement about a vertical axis, the boom 3 pivoted to the bed on a horizontal axis, means for rotating the boom A rope 14 is attached to the boom` aboutits horizontal! axis, and means for suspending loads from the boom in such a manner that the rotation of the boom around the horizontal axis 4 will increase or decrease the working radius of the crane.

My invention consists in making a part of the crane in the form of oney or more Weights connected directly or indirectly to the rotatable bed in such a way as to be movable in'a ,direction approximately parall'elI to thellongitudinal center line of the bed, together with suitable actuating mechaso connected directly or indirectly with the boom, that when the workinvradius is vari d' by varying the position o the boom with relation to a horizontal plane, the weight isV moved in a direction opposed to theifdirection of movement of the lifting tackle, and to such an extent that the center of gravity ol the bed and all parts of the .cranjeicarried thereby, exclusive of loads,

will remainwithin predetermined limits.

l yI have shown in the accompanying drawingf'the manner in which I now prefer to construct the counterweight mechanism. As

there shown, weights- `are mounted on axles 21 which carry outer wheels 22 and inner wheels` 23 and 24 running on xed rails 25 and 26` respectively, these rails being se` cured, as shown, to vertical plates 27 and 2S forming part of the Vframework of the bed 2. Spur gear wheels 29 are formed integral i with, or rigidly connected to, the inner Y wheels 23 and 24, the pitch diameter of the gears 29 being the same as the diameter of the treads ofthe wheels 23 and 24. The

' wheels 24', in addition to the gears 29, also CTI have spur gears30, the Vpitch diameters of which must be larger or smaller than those of the vgears 29 integral with or connected to them, thepitch diameter of the gears 30 being, for the arrangement here shown, less than the pitch diameters of the gears 29.

`The gears 29 meshV with'stationary racks 31 whichr are rigidly connected to the bed 2.

`and have their pitch lines parallel to the tracks 26.V The teeth of the smaller gears 30 vmesh'with sliding racks 32 which are slidably mounted in the hed 2 so as to be movable parallel to the tracks 26. As shown in Fig. 5, the fixed rack 3l is formed from an angle bar, the lower flange of which supports the sliding rack 32.

For the purpose of connecting the slidingV racks 32 so as to move them in correct response to 'vertical swinging movements of theboom 3, these sliding racks may be broadened at their ends near the pivot pins 4 as shown at 33, and may have, integral with or rigidly attached to them, yokes 34 having slotsy 35 engaging pins 36 carried by cranks 37 which are rigidly attached to the i boom-3 so that any movement of the boom around itspiyotpins 4, will cause a corresponding movement oi the pins 36 which will, in turn, impart to the yokes 34 and the sliding racks 32 a movement determined by the shape of the slots 35, the length ol` cranks 37, and the location of pins 36 in relation to the center line of the boom The sliding racks 32, the gears 29 and 30, and the stationary racks 3l, form a differential system, whereby downward swinging movement of the load-supporting end of the boom, which increases the working radius of the crane, will be accompanied by movement of weights 2O away from the lifting tackle. That is to say, when the outer end of the boom is lowered, the weiehts will move to the left in Figs. l to 4. likewise, i

when the outer end ot the boom is raised the weights will move in the opposite direction, or to the right in Figs. l to 4.

This action may be best understood by referring to Fig. 3, where A is the point of tangency between the gear 29 and the stationary rack 3l; B is the point of tendency between the smaller gear 3() and the movable rack 32; and C is the common center ot gears 29 and 30. Since the rack 3l is stu.- tionary, the point A is the instantaneous center or fulcrum 'point for the gear 29, and also for the gear 30, since these gears are rigidly connected. Therefore, the movements of all points of gears 29 and 3() are .1'

proportional to their respective distances from an axis through the point A parallel to the axis of the shaft 2l.

Let it now be assumed that the upper end of the boom is lowered, thereby sliding the rack 32 to the left in Fig. 3. This pushes to the left the tooth oil the gear 3() which is in engagement at B with the sliding rack 32, and the gear 29 is swung to the left around its fulcrum A. As the first tooth ot the gear 30 at the point B becomes disengaged from the sliding rack 32, the next tooth engages the rack and the action is thus continuons, producing a rol-ling movement ot the large gear 29 to the left on the stationary rack 3l. The same action ot course takes place in the gearing at the other side of the crane. lVhen the boom is raised, the same movement takes place, but in the reverse direction. y

It is evident that the amount oi movement of the weights 20 produced by a given swinging movement of the boom 3 may be changed by varying thc relation between the radii of the gears 29 and 30, and that it gear 30 were made larger than gear 29 the weights 2() would move in the opposite direction to racks 32. Also if the construction of the crane is such that pins 36 may more conveniently be placed above pins 4, the movement of racks 32 will be in the opposite direction as regards its relation to movements of the boom` in which case the gear 3() should be made larger than the gear 29, causing weights 2O to move in the opposite dilll] rection to racks 32, the double reversal restoring the proper relation between the movements of the boom 3 and thel weights 20.

As a modilication of the gearing which communicates movement from the boom 3 to the weights 20, the gear wheels 29 and 30 may, as shown in Figs. 7 and 8, be mounted on a shaft 38 which is separate from the axles 2l, and this shaft need not be horizontal. If the gears are mounted on a separate shaft there is of course no necessary relation between the diameters of these gears and the diameters of the smooth wheels 22, 23 and 24.

Fig. 6 shows a modified method of connecting the lower end of the boom 3 to the sliding racks 32, wherein I employ a linkage. As shown in Fig. 6, 56 is a link loosely pivoted to the crank 37 by means of a pin 57 and is similarly connected to the rack 32 by means of a pin 58.

I am aware that various methods have been used for applying movable counterweights to cranes, but most of these have been employed for the purpose of counterweighting a part of the load, or it has been necessary to adjust the counterweight to the load. In my invention, on the contrary, the only parts counter-weighted by the movable weights 20 are the boom and the other parts carried by the bed, which have a horizontal displacement when the working radius is varied, exclusive of the load. The principle of my invention thus consists in the use of auxiliary movable counterweights suiiicient only for partially or fully counterbalancing a hinged boom and its associated parts only, the weights beinv connected to the boom directly or indirectsly so as to render them automatically adjustable to the boom position.

In Fig. l the vertical line XY is assumed to be at such a distance from'the vertical axis of rotation of the bed that when the center of gravity of the bed, and all parts of the crane carried by it (but not including any loads), is on the vertical line XY the center of gravity of the whole crane will be, for some position of the bed in its rotation about the vertical axis, as far from this axis as is consistent with safety against overturni ing, say in the vertical line ST. Any horizontal movement of the center of gravity of the bed and parts carried by it will cause a similar movement of the center' of gravity of the whole crane in the same direction. Therefore, movement of the center of gravity of the bed and all parts carried by it to the left of the line XY is a condition not to be considered except in the special case of some part having been temporarily removed, or the position of the bed restricted to some position of greater stability. Any movement of this center of gravity to the right of the line XY will reduce the supporting capacity of the crane. The size and position of the weights 20, and their operative relation to the boom 3, should therefore be so selected that the center of gravit of the bed, and all parts carried by the be is kept as nearly as possible on the line XY, for all working radii for which the maximum lifting capacity is desired, consistent with safety against backwardA overturning.

Wlhile I have shown and described a prefer-red method of moving the movable weights in response to movement of the boom, it will be understood that my invention is not restricted to this particular' mechanism, but includes broadly any means by which vertical swinging movement of the boom automatically produces the desired movement of the movable weight or weights. It will also be understood that the details of construction shown and described may be otherwise modified in many respects without departing from my invention, the scope of which is indicated in the appended claims.

I claim as my invention:

l. In a crane, the combination of a bed, a boom mounted on said bed for vertical swinging movement on a horizontal axis, track carried by said bed, a weight having wheels running on said track, and connections between said weight and said boom` whereby said weight is caused to approach the lo-ad-supporting portion of said boom solely in response to rising movement of said portion of the boom, andis caused to recede from the load-supporting portion o-f said boom solely in response to the lowering movement of said portion ofthe boom, the position of said weight being at all times independent of the load carried by the crane. r A

2. In a crane, the vcombination of a bed mounted for rotation about a vertical axis, a boom mounted on said bed for vertical swinging movement about a horizontal axis, means for varying the inclination of said boom in relation to a horizontal plane, means for suspending lifting tackle from said boom, weights carried by said bed and movable in am direction approximately parallel to the longitudinal center line of said bed. and automatic means for moving said weights solely in response to vertical swinging movement of said boom so as to maintain the center of gravity of said bed and all parts carried thereby exclusive of loads, within predetermined limits in relation to said bed for all working positions of said boom, the position of said weight being at all times independent of the load carried by the crane.

3. In a crane, the combination of a bed mounted for rotationl about a vertical axis, a boom mounted on said bed for vertical swinging movement about a horizontal axis, means for varying the inclination of said boom in relation to a horizontal plane, means for suspending lifting tackle from said boom, Va plurality of tracks carried by said bed, Weights having Wheels running on said tracks and movable in a direction approximately parallel to the longitudinal center line of said bed, stationary racks carried byY said bed and parallel to said tracks, gear Wheels carried by said Weights and meshing with said stationary racks, other gear Wheels coaxial with and rigidly attached to said iirst-named gear Wheels, longitudinally slidable racks carried by said bed, said slidable racks being parallel to said stationary racks and meshing with said second-named gear Wheels, and mea-ns for moving said slidable racks in response to vertical swinging movement of said boom, and `tor thereby moving said Weights so as to maintain the center' of gravity Ot said bed and all parts carried thereby exclusive of loads, Within predetermined limits with respect to said bed for all Working positions ot said boom.

4. In a crane, the combination of a bed mounted tor rotation about a vertical axis, aboom mounted on said bed for vertical swinging movement about a horizontal axis, means for varying the inclination of said boom in relation to the horizontal plane, means for suspending lifting tackle from said boom, a plurality ot tracks carried by said. bed, Weights having wheels ruiming on said tracks and movable in a direction approximately parallel to the longitudinal centerV line of said bed, stationary racks carried by saidbed and parallel to said tracks, gear Wheels carried by said weights and meshing .'ivithjsaid stationary racks, other gear Wheels coaxial with and rigidly attached to said first-named gear Wheels, longitudinally slidable racks carried by said bed, said slidable racks being parallel'to said stationary racks and meshing with said second-named gear Wheels, and cranks carried by said boom and operatively connected to move said slidable racks in response to vertical swinging movement of said boom lor the purpose oiv moving said weights so as to maintain the center of gravity ot said bed and all parts carried thereby, exclusive of loads, within predetermined limits with re spect to said bed lor all working positions of said boom.

5. In a crane, the combination of a bed mounted ior rotation about a vertical axis. a hoorn mounted on said bed for vertical swinging movement about a horizontal axis. means for varying the inclination oi said boom in rela-tion to a horizontal plane, means for suspending li t'ting tackle from said boom, a plurality ot tracks carried by said bed, weights having Wheels ruiming on said trac (s and movable in a direction approxi mately parallel to the longitudinal center line of said bed, stationary racks carried by said bed and parallel to said tracks, gear Wheels carried by said Weights and mesh ing With said stationary racks, other gear wheels coaxial with and rigidly attached to said hist-named gear Wheels, longitudinally slidable racks carried by said bed, said slidable racks being parallel to said stationary racks and meshing with said second-named gear Wheels, cranks carried by said boom, pins carried by said cranks and members carried by said slidable racks having slots for receiving said pins, whereby vertical swinging movement of said boom imparts sliding movement to said slidable racks and thereby moves said Weights so as to main tain the center ol gravity of said bed and all parts carried thereby exclusive of loads, Within predetermined limits with respect to said bed for all working positions of said boom.

In testimony whereof I, the said ALLAN E. JOHNSON, have hereunto set inv hand.

ALLAN E. JOHNSON. 

